I would say that the two indexes that you really should need for this query is:
bars(shoolId)
events(barId,sortDate)

The reason:
1. You are using a LEFT JOIN which forces MySQL to always join using the bars table first. Which means that you should first find these records.

2.
You are only using e.barId and sortDate in the ON condition.

That query should do pretty OK with just those two indexes.
And yes you could add some more columns to the right side of these columns in the index if you want to avoid additional seeks, but that would also increase the index size and you are selecting so many fields that I don't think it will benefit from it.